Personal tools

Information zum Seitenaufbau und Sprungmarken fuer Screenreader-Benutzer: Ganz oben links auf jeder Seite befindet sich das Logo der JLU, verlinkt mit der Startseite. Neben dem Logo kann sich rechts daneben das Bannerbild anschließen. Rechts daneben kann sich ein weiteres Bild/Schriftzug befinden. Es folgt die Suche. Unterhalb dieser oberen Leiste schliesst sich die Hauptnavigation an. Unterhalb der Hauptnavigation befindet sich der Inhaltsbereich. Die Feinnavigation findet sich - sofern vorhanden - in der linken Spalte. In der rechten Spalte finden Sie ueblicherweise Kontaktdaten. Als Abschluss der Seite findet sich die Brotkrumennavigation und im Fussbereich Links zu Barrierefreiheit, Impressum, Hilfe und das Login fuer Redakteure. Barrierefreiheit JLU - Logo, Link zur Startseite der JLU-Gießen Direkt zur Navigation vertikale linke Navigationsleiste vor Sie sind hier Direkt zum Inhalt vor rechter Kolumne mit zusaetzlichen Informationen vor Suche vor Fußbereich mit Impressum

Document Actions

RG Dr. Daniel Schröder

Welcome to the website of the junior research group Dr. Daniel Schröder!
Selected results
Selected results

July 2019

Rechargeable metal-oxygen batteries are considered as a potential technology in future energy storage systems. Alkali metal-oxygen batteries, such as lithium-oxygen batteries, are in particular focus of industry and research due to their high theoretical energy density. The lithium peroxide formed during discharge precipitates as a solid on the cathode structure, so the cathode design and understanding of the growth mechanism play a crucial role in achieving maximum energy densities. For this reason, the BMBF-project MeLuBatt – in close cooperation with the Institute for Energy and Systems Engineering (InES) at TU Braunschweig and the Fraunhofer Institute for Manufacturing Technology and Applied Materials Research (IFAM) in Oldenburg – is currently investigating the growth behaviour of the discharge product in the cathode of lithium oxygen batteries. The SEM image shows the magnification of a carbon fiber on which toroid-like Li2O2 particles have been formed. The size and particle density of these toroids strongly depends on the availability of dissolved oxygen in the electrolyte: With more dissolved oxygen (cathode side facing the O2 reservoir), fewer but significantly larger toroids are formed, while deeper in the electrolyte (cathode facing the separator side) the toroids are smaller, but grow in a higher density. The diagram schematically illustrates how the size and density of the toroids depend on the dissolved O2 in the electrolyte along a carbon fiber. (Picture submitted by Julian Kreißl, Daniel Langsdorf and Daniel Schröder).
July 2019
Full-size image: 2.19 MB | View image View Download image Download

November 2018

Redox flow batteries are suitable for the stationary storage of intermittent energy provided by renewable energies. The beneficial design of the redox flow battery enables the storage of energy in liquid electrolytes in different oxidation states outside the actual electrochemical cell. Currently, the active material dissolved in the electrolyte constitutes the main cost factor for redox flow batteries. Using cheaper organic molecules instead, that for example may be obtained by purification of waste products from the pulp and paper industry, could save costs and further increase the economic viability of redox flow batteries. In the search for a suitable molecule that fits this application, the BMEL project FOREST is currently investigating several organic molecules for their stability and performance. The picture shows the measurement setup used for a lab-sized redox flow battery (center). The dissolved active materials – here in the form of an organic electrolyte on the anode and a vanadium (IV) based electrolyte on the cathode side – are transported into the electrochemical cell by pumps. A reference electrode allows for the recording of the working (WE) and counter electrode (CE) potentials during battery cycling and therefore enables to draw conclusions about the performance and degradation behavior of the associated active materials (right). Picture submitted by Dominik Emmel and Jonas Hofmann, RG Dr. Daniel Schröder
November 2018
Full-size image: 3.33 MB | View image View Download image Download

February 2018

Do we always get ZnO as discharge product in electrically rechargeable zinc–air batteries? Nowadays, air breathing batteries appear as a good alternative to overcome our increasing demand of energy. One of the best candidates regarding its cost of production, recyclability and safety is the electrically rechargeable Zn/air battery. Therefore, the development of the rechargeable Zn/air battery has attracted much attention and received an intense research effort to extend its cycling stability. One key issue in alkaline electrically rechargeable Zn/air battery is the electrochemical reaction at the Zn electrode. ZnO as discharge product cannot be fully converted to Zn. In general, the formation of ZnO is influenced by many parameters such as local concentration, pH and diffusion of Zn ions species in alkaline solution. However, the nucleation and growth of ZnO in electrically rechargeable Zn/air battery can be also influenced by an interaction between discharge and charge process. We observed that a battery component, such as a Sn current collector, could also affect the nature of the discharge product during cycling. The scanning electron micrograph (figure below) shows orthorhombic ZnSnO3 or Zn2SnO4 crystallites surrounded by many hexagonal tubes of ZnO obtained after 25 cycles on top of the Zn electrode. These new investigations are part of the ongoing German-Japanese BMBF joint project ‘Zisabi’ to gain a deeper insight into electrically rechargeable Zn/air batteries. (Picture submitted by Saustin Dongmo and Daniel Schroeder.)
February 2018
Full-size image: 291 KB | View image View Download image Download

October 2017

The electrochemical synthesis from Ionic Liquids (ILs) offers an alternative route for the formation of unusual noble metal compounds, like silver oxides. A major advantage of this route is the possibility to work in the absence of harsh conditions like high pressures or temperatures and the use of highly reactive and/or hazardous educts. This approach is analogous to the reactions in a metal air battery, where oxygen is reduced to superoxide at the cathode (Red1: O2 + e– → O2–) and metal oxidized to the corresponding metal ions (Ox, here: Ag → Ag+ + e–). These can precipitate together as a metal oxide (here: AgxOy) and/or undergo further disproportionation. However, the metal ions compete with the oxygen of the reduction at the cathode and the inverse reaction to Ox can occur (Red2: Ag+ + e– → Ag) instead of the wanted oxygen reduction reaction (ORR).A pure oxygen saturated IL ([Pyr13][TFSI]) shows a clear ORR signal (Red1) in the cyclic voltammogram at -1.17 V (left figure, blue line). After the addition of the corresponding silver salt (Ag[TFSI]) the peak vanishes and another redox potential at -0.38 V appears, which corresponds to the Ag/Ag+ potential. Thus, unlike in metal air cells, no reaction of oxygen and silver to the metal oxide (Red1 and Ox) is observable. Instead, pure silver is deposited on the cathode and the ORR is suppressed (Red2 and Ox). The right figure shows the porous morphology of the deposited silver.The major target of this project is a better understanding of the occurring reduction reactions Red1 and Red2 depending on parameters like temperature, scan rate, potential, O2- and Ag-concentration. (Picture submitted by Peter Schmitz)
October 2017
Full-size image: 439 KB | View image View Download image Download

October 2016

In view of the fact that the establishment of alternative energy sources is coupled to the storage of the so generated energy different concepts of stationary energy storage are being investigated at the moment. Besides conventional battery systems like lithium-ion batteries alternative storage solutions that are based on abundant and cost efficient materials enter the limelight. For example several organic molecules that can be obtained by many kinds of resources can be optimized for their application in electrochemical cells. The desired molecules for this application are being defined within the scope of a collaboration between the Physical-Chemical- and the Organic Institute of the Justus-Liebig University by the investigation of the correlation between their structure and electrochemical properties. One important way to have an influence on these properties is to vary the pH value of the electrolyte the electrochemically active species is dissolved in. By modifying it the potential of the electron transfer can be varied to optimize the compound for the application in different environments. The image shows the influence of the pH value on the compounds charge transfer characteristic by shifting its potential. This is illustrated by cyclic voltammogramms that have been measured versus a Ag/AgCl reference electrode within a three-electrode assembly. (Picture submitted by Jonas Hofmann.)
October 2016
Full-size image: 79 KB | View image View Download image Download